| 12601 | COSU | CHINA OCEAN STEAMSHIP LTD | | | SCAC3 |
| 12602 | COSU | CHINA OCEAN SHIPPING COMPANY | | | SCAC4 |
| 12603 | COSW | CROSSOCEAN SHIPPING CO., INC. | | | SCAC3 |
| 12604 | COSW | COASTAL AIR FREIGHT | | | SCAC4 |
| 12605 | COSX | Cabot Corp., CAB-O-SIL Division | added 7/1985; 1/1994-7/2000; eliminated 10/2000; 7/2005 (not listed) | | NAKINA |
| 12606 | COSX | D-X Sunray Oil Co. | 10/1957; eliminated 10/1959 | | NAKINA |
| 12607 | COSX | Mid-Continent Petroleum Corp. | 7/1937-7/1954 | | NAKINA |
| 12608 | COSX | Cosden & Co. Mid-Continent Petroleum Corp. | 7/1935 | | NAKINA |
| 12609 | COSX | Cosden & Co. | 8/1920-7/1932 | | NAKINA |
| 12610 | COSX | Mid-Continent Petroleum Corp. | 4/38-1/52 | | NRHS |
| 12611 | COSX | D-X Sunray Oil Co. | 10/57; eliminated 10/59 | | NRHS |
| 12612 | COSX | Cabot Corp., CAB-O-SIL Division | 1/94-7/2000; eliminated 10/2000 | | NRHS |
| 12613 | COSX | *COSDEN & CO. | | | PWRC |
| 12614 | COSX | *CITY OF SPENCER | | | PWRC |
| 12615 | COSX | +CABOT CORPORATION, CAB-O-SIL DIVISION [D-X SUNRAY OIL CO.; MID-CONTINENT PETROLEUM CORP.] | | | PWRC |
| 12616 | COSX | Cabot Corporation (CAB-O-SIL Division) | | | RSRV |
| 12617 | COSX | CABOT CORPORATION, CAB-O-SIL DIVISI | | | SCAC4 |
| 12618 | COSX | Cosden & Co. Mid-Continent Petroleum Company | | USA | TRAFFIC |
| 12619 | COSZ | COAL SPRING INDUSTRIES | | | PWRC |
| 12620 | COT | Cottesmore FTU | Callsign: Cottesmore, ICAO callsign changed from Crater | GB | AVCODES |
| 12621 | COT | Cottesmore FTU | Callsign: Crater, ICAO callsign changed to Cottesmore | GB | AVCODES |
| 12622 | COT | Costa Airlines, C.A. | Callsign: Coair, | YV | AVCODES |
| 12623 | COT | Cottesmore Flying Training Unit | | | ICAO1 |
| 12624 | COT | Central Ontario Ry. (Canadian National Rys.) | 8/1920-7/1923 | | NAKINA |
| 12625 | COT | Central Ontario Ry. (Canadian National Rys.) | 23-Jul | | NRHS |
| 12626 | COT | *CANADIAN NATIONAL RWY. [CENTRAL ONTARIO RWY.] | | | PWRC |
| 12627 | COT | *CITY OF TAMPA | | | PWRC |
| 12628 | COT | *RETIRED 08-26-93 ATP | | | PWRC |
| 12629 | COT | COLONIAL TRAILWAYS | | | SCAC4 |
| 12630 | COT | | City: Cottbus | D | TRAFFIC |
| 12631 | COTA | CONTRACT TRANSPORT SERVICE INC | | | SCAC3 |
| 12632 | COTA | Central Ohio Transit Authority | | USA | TRAFFIC |
| 12633 | COTB | COLOR TILE SUPERMARTS INC | | | SCAC3 |
| 12634 | COTC | COMMERCIAL TRAFFIC SERVICES | | | SCAC3 |
| 12635 | COTC | COLE OIL & TIRE CO INC | | | SCAC4 |
| 12636 | COTE | COTE R INC | | | SCAC3 |
| 12637 | COTE | COTTER, E P OIL CO INC | | | SCAC4 |
| 12638 | COTF | COSTELLO, FRANK J JR | | | SCAC3 |
| 12639 | COTG | COTTER MOVING & STORAGE COMPANY, TH | | | SCAC3 |
| 12640 | COTH | COLE, THOMAS E | | | SCAC4 |
| 12641 | COTI | CONTI TRUCKING INC | | | SCAC3 |
| 12642 | COTI | CORNIVER TECHNOLOGIES INC | | | SCAC4 |
| 12643 | COTJ | COWEN TRUCK LINE INC | | | SCAC3 |
| 12644 | COTJ | COWEN TRUCK LINE INC | | | SCAC4 |
| 12645 | COTK | COTTER TRUCKING COMPANY INC | | | SCAC4 |
| 12646 | COTL | CONTINENTAL TRANSPORTATION LINES | | | PWRC |
| 12647 | COTL | COTTRELL TRUCK LINES INC | | | SCAC3 |
| 12648 | COTL | COTTRELL TRUCK LINES INC | | | SCAC4 |
| 12649 | COTM | COTE, MIDDY | | | SCAC3 |
| 12650 | COTM | CONTINUUM TRANSPORTATION SERVICES L | | | SCAC4 |
| 12651 | COTN | COTTON, RICHARD E | | | SCAC3 |
| 12652 | COTN | CORETRANS LLC | | | SCAC4 |
| 12653 | COTO | COTTLES TRUCKING AND FUEL SERVICE | | | SCAC3 |
| 12654 | COTO | COUNTRY TRANSPORT | | | SCAC4 |
| 12655 | COTP | COTE, LOUIS P, INC | | | SCAC3 |
| 12656 | COTQ | COLONIAL TANK TRANSPORT | | | SCAC3 |
| 12657 | COTQ | COASTAL TRUCKING CO INC | | | SCAC4 |
| 12658 | COTR | CHAMPION DIVISION TRUCKS | | | SCAC3 |
| 12659 | COTR | CLASS ONE TRANSPORT LLC | | | SCAC4 |
| 12660 | COTR | Compagnie des transports angevins | City: Angers | F | TRAFFIC |
| 12661 | COTRA | Cotra Logistics Solutions BV | | NL | TRAFFIC |
| 12662 | COTS | COMPTON TRANSFER & STORAGE CO | | | SCAC4 |
| 12663 | COTS | Cotswold Rail | Real: CR, Cotswold Rail is a spot-hire company of shunting and mainline locomotives, based in Moreton-in-Marsh, Gloucestershire. | GB | TRAFFIC |
| 12664 | COTT | CONTINENTAL TRANSPORT SYSTEMS INC | | | SCAC3 |
| 12665 | COTT | CAPITAL 1 TRANSPORT LLC | | | SCAC4 |
| 12666 | COTU | CONTARES-CONQUEREL | | | SCAC3 |
| 12667 | COTU | RABANCO COMPANIES | | | SCAC4 |
| 12668 | COTV | CONTINENTAL VAN LINES | | | SCAC3 |
| 12669 | COTX | GLNX Corp. | added 1/1996; eliminated 7/1998; 7/2000-7/2005 (not listed) | | NAKINA |
| 12670 | COTX | Jansen Rail Car, Inc. | added 4/1989; 1/1994; eliminated 1/1996 | | NAKINA |
| 12671 | COTX | Consolidated Transportation Corp. | added 1/1981; eliminated 1/1989 | | NAKINA |
| 12672 | COTX | Cudahy Packing Co. | 1/1945-4/1947 | | NAKINA |
| 12673 | COTX | Cudahy Car Lines | 4/1938-1/1943 | | NAKINA |
| 12674 | COTX | The Cudahy Oil Tank Line (Cudahy Car Lines) | 7/1932-7/1937 | | NAKINA |
| 12675 | COTX | The Cudahy Oil Tank Line | 7/1923-7/1930 | | NAKINA |
| 12676 | COTX | Consolidated Transportation Corp. | added 1/81; eliminated 1/89 | | NRHS |
| 12677 | COTX | The Cudahy Oil Tank Line (Cudahy Car Lines) | Apr-38 | | NRHS |
| 12678 | COTX | Jansen Rail Car, Inc. | added 4/89; 1/94; eliminated 1/96 | | NRHS |
| 12679 | COTX | GLNX Corp. | added 1/96; eliminated 7/98; 7/2000 | | NRHS |
| 12680 | COTX | *CUDAHY PACKING CO. [CUDAHY TANK LINES] | | | PWRC |
| 12681 | COTX | *JANSEN RAILCAR, INC. [CONSOLIDATED TRANSPORTATION CORP.] | | | PWRC |
| 12682 | COTX | +GLNX CORPORATION | | | PWRC |
| 12683 | COTX | Consolidated Transportation Corporation (GLNX Corporation) | | | RSRV |
| 12684 | COTX | GLNX CORPORATION | | | SCAC4 |
| 12685 | COU | Airlines of Carriacou Limited | Callsign: Air Carriacou, | WG | AVCODES |
| 12686 | COU | Airlines of Carriacou Limited | IATA: C4, Designator C4 recalled by IATA | WG | AVCODES |
| 12687 | COUA | COURAGEOUS LAKE CARIBOU CAMPS | | | SCAC4 |
| 12688 | COUB | COURTNEY VAN LINES INC | | | SCAC3 |
| 12689 | COUC | COURTOIS, RICHARD ALFRED | | | SCAC3 |
| 12690 | COUC | COUS TRANSPORT SYSTEMS INC | | | SCAC4 |
| 12691 | COUD | COUSINOS BODY SHOP, INC | | | SCAC3 |
| 12692 | COUF | COUTU BROS MOVERS INC | | | SCAC3 |
| 12693 | COUH | COUNCILL HAULING INC | | | SCAC3 |
| 12694 | COUH | COTEAU HILLS TRANSPORT LTD | | | SCAC4 |
| 12695 | COUI | COULTER, A W TRUCKING | | | SCAC3 |
| 12696 | COUI | COULTER, A W INC | | | SCAC4 |
| 12697 | COUJ | COUNTRY MISS INC | | | SCAC3 |
| 12698 | COUL | COUSINS LEASING CORPORATION | | | SCAC3 |
| 12699 | COUL | COULOMBE, LUCIEN LTD | | | SCAC4 |
| 12700 | COUM | COUNTY MOVING AND STORAGE CO INC | | | SCAC3 |
